Field of the Invention
The present invention relates generally to medical systems and procedures and more particularly to devices and methods of their use for injection of a therapeutic agent into the surface of an interior body cavity of a living being.
Background Information
Market expansion in cardiovascular and cardiothoracic surgery in past years has largely been driven by increases in open-heart surgical bypass procedures, but new opportunities for growth will come from products associated with least-invasive procedures. The positive outcomes seen thus far with these techniques, accompanied by continued physician acceptance, will lead to a gradual erosion of the market for traditional open-heart surgery.
Driven by capitation and cost-cutting measures associated with managed care, these evolving techniques and procedures not only hold the promise of reduced trauma to patients, but also reduce the significant costs associated with traditional open-heart surgery. Markets for least invasive approaches to cardiothoracic surgery, including equipment and disposables, are predicted to grow at tremendous rates for the next twenty years.
Within the past few years, an increasing number of centers worldwide have begun performing revolutionary techniques, such as beating-heart coronary artery bypass and laser transmyocardial revascularization (TMR). These developing procedures offer the potential of expanding the size of the eligible patient base by providing significantly reduced patient trauma and lower costs, as well as providing a viable alternative to patients unable to undergo open heart surgery.
Bone marrow cells and liquid aspirate are believed to be the source of angiogenic peptides known as growth factors. In addition, recent studies have shown that bone marrow cells include stem cells that differentiate into angioblasts. Angiogenesis represents the postnatal formation of new blood vessels by sprouting from existing capillaries or venules. During angiogenesis, endothelial cells are activated from a quiescent microvasculature (turnover of thousands of days) to undergo rapid proliferation (turnover of a few days).
In one technique currently in clinical stage testing, autologous bone marrow cells are transplanted into the heart to restore heart function. In one such procedure, autologous bone marrow cells obtained by aspiration from the patient""s hipbone are transplanted into transventricular scar tissue for differentiation into cardiomyocytes to restore myocardial function (S. Tomita, et al., Circulation 100:19 Suppl II 247-56, 1999). In another technique, autologous bone marrow cells are harvested and transplanted into an ischemic limb or ischemic cardiac tissue as a source of angiogenic growth factors, such as VEGF (A. Sasame, et al., Jpn Heart J, Mar 40:2 165-78, 1999).
To perform such techniques, various types of needles and needle assemblies used for bone marrow biopsy, aspiration, and transplant have been proposed and are currently being used. Many such bone marrow harvesting devices include a cannula, stylet with cutting tip, or trocar that can be used to cut a bone marrow core sample. On the other hand, devices designed for withdrawal of liquid bone marrow aspirate typically comprise a large gauge hollow needle attached to a device for creating a negative pressure to aspirate the liquid bone marrow.
Current procedures used for harvesting, purification and reinjection of autologous bone marrow cells may require sedation of the patient for a period of three to four hours while the bone marrow aspirate is prepared for reinjection. In addition, the present procedure involves great risk of infection for the subject because the harvested bone marrow material is routinely aspirated in an operating or recovery room and then transferred after aspiration to a laboratory where the aspirate is placed into a centrifuge for gravity separation of bone marrow cells from the aspirate. In many cases the bone marrow aspirate is transferred into a specially designed centrifuge tube for the gravity separation. The separated bone marrow cells are then removed from the centrifuge tube into a syringe and transferred back to the recovery room or operating room for reinjection into the patient. Thus, the bone marrow aspirate is handled under potentially non-sterile conditions and reinjected into the patient as a potentially non-sterile preparation.
Generally, the processed cells are injected by catheter into the ischemic site where reperfusion is required. For example, it is known to deliver bone marrow cells by pericardial catheter into the subject""s myocardium to stimulate angiogenesis as a means of reperfusing ischemic tissue with collaterally developed capillaries. However, prior art methods for preparation and injection of non-sterile bone marrow aspirate risk introduction of pathogens with consequent increased risk of infection for the patient.
Angiogenic peptides like VEGF (vascular endothelial growth factor) and bFGF (basic fibroblast growth factor) have also entered clinical trials for treatment of coronary artery disease. Attempts are being made to devise clinically relevant means of delivery and to effect site-specific delivery of these peptides to ischemic tissue, such as heart muscle, in order to limit systemic side effects. Typically cDNA encoding the therapeutic peptide is either directly injected into the myocardium or introduced for delivery into a replication-deficient adenovirus carrying the cDNA to effect development of collateral arteries in a subject suffering progressive coronary occlusion.
Recently, various publications have postulated on the uses of gene transfer for the treatment or prevention of disease, including heart disease. See, for example, Mazur et al., xe2x80x9cCoronary Restenosis and Gene Therapy,xe2x80x9d Molecular and Cellular Pharmacology, 21:104-111, 1994; French, xe2x80x9cGene Transfer and Cardiovascular Disorders,xe2x80x9d Herz 18:222-229, 1993; Williams, xe2x80x9cProspects for Gene Therapy of Ischemic Heart Disease,xe2x80x9d American Journal of Medical Sciences 306:129xe2x80x94136, 1993; Schneider and French, xe2x80x9cThe Advent of Adenovirus: Gene Therapy for Cardiovascular Disease,xe2x80x9d Circulation 88:1937-1942, 1993. Another publication, Leiden et al, International Patent Application Number PCT/US93/11133, entitled xe2x80x9cAdenovirus-Mediated Gene Transfer to Cardiac and Vascular Smooth Muscle,xe2x80x9d reports on the use of adenovirus-mediated gene transfer for the purpose of regulating function in cardiac vascular smooth muscle cells. Leiden et al. states that a recombinant adenovirus comprising a DNA sequence that encodes a gene product can be delivered to a cardiac or vascular smooth muscle cell and the cell maintained until that gene product is expressed. According to Leiden et al., muscle cell function is regulated by altering the transcription of genes and changes in the production of a gene transcription product, such as a polynucleotide or polypeptide. Leiden et al. describe a gene transfer method comprising obtaining an adenoviral construct containing a gene product by co-transfecting a gene product-inserted replication deficient adenovirus type 5 (with the CMV promoter) into 293 cells together with a plasmid carrying a complete adenovirus genome, such as plasmid JM17; propagating the resulting adenoviral construct in 293 cells; and delivering the adenoviral construct to cardiac muscle or vascular smooth muscle cells by directly injecting the vector into the cells.
There are impediments to successful gene transfer to the heart using adenovirus vectors. For example, the insertion of a transgene into a rapidly dividing cell population will result in substantially reduced duration of transgene expression. Examples of such cells include endothelial cells, which make up the inner layer of all blood vessels, and fibroblasts, which are dispersed throughout the heart. Targeting the transgene so that only the desired cells will receive and express the transgene, and the transgene will not be systemically distributed, are also critically important considerations. If this is not accomplished, systemic expression of the transgene and problems attendant thereto can result. For example, inflammatory infiltrates have been documented after adenovirus-mediated gene transfer in liver (Yang, et al. Proc. Natl. Acad Sci. (U.S.A.) 91:4407, 1994). Finally, with regard to adenovirus-mediated gene transfer of FGF-5 for the in vivo stimulation of angiogenesis, it is known that in some cases the injected viral material can induce serious, often life-threatening cardiac arrhythmias.
It is also known to transfect autologous bone marrow cells obtained as described above with such adenovirus transformed with cDNA encoding such therapeutic peptides for in vivo expression of the angiogenic peptides at the ischemic site. However, the handling of adenovirus vectors is generally considered a risk to the medical team members responsible for their preparing and handling and/ or their injection into patients. For this reason, current practice is to prepare the vectors and transform the bone marrow cells xe2x80x9cunder the hoodxe2x80x9d to curtail possible escape of the adenovirus, thus requiring transport of the bone marrow to a laboratory for transfection and then return to the patient for injection of the transfected cells.
Least-invasive methods of treatment wherein a therapeutic agent, such as an angiogenic agent, is injected by catheter into an interior body site also raise the difficult problem of controlling the location injected as well as the depth and amount of therapeutic agent injected. For example, the amount of extraneously introduced angiogenic growth factor, such as VEGF, that can be tolerated by the subject is very small. At high doses VEGF is known to cause a drop in blood pressure. Over dosage has proven to be fatal in at least one clinical trial. Thus strict control of the amount of growth factor delivered is of great importance. In addition, since the delivery site is located along the surface of an interior body cavity, such as the myocardium, a deflectable intravascular catheter with an infusion needle is customarily used, but it is difficult to control the location and angle of penetration of the myocardium to effect uniformly spaced delivery of uniform amounts of the therapeutic agent.
In some cases, controlling the depth of needle penetration is complicated by the tendency of prior art steerable infusion catheters to withdraw the needle into the catheter when the catheter is deflected to approach the wall of an internal organ. In compensation for needle withdrawal, it is current practice to advance the needle from the tip of the catheter an extra distance. In some cases, where the catheter is advanced into the pericardial space to deliver a therapeutic fluid into the myocardium, the needle has actually punctured the wall of the heart, by over penetration with the result that the therapeutic fluid is not introduced into the myocardium at all.
Many therapeutic substances other than angiogenic agents are also introduced into the surface of interior body cavities. For example, the reverse of angiogenesis is practiced for a number of therapeutic purposes, such as the prevention of restenosis following a reperfusion procedure or in treatment of diabetic retinopathy and various types of cancer. In anti-restenosis, the growth of new blood vessels is blocked or curbed and the formation of new tissue (e.g., a growing tumor, neointima on the surface of a stent or vascular prosthesis, etc.) is limited or eliminated by introduction of xe2x80x9creverse angiogenesisxe2x80x9d agents, such as angiostatin, endostatin or, antarin, a locally administered mitotoxin that inhibits cell proliferation into the tissue.
Thus, there is a need in the art for new and better equipment for use in handling and treating autologous bone marrow and for controlled delivery of fluid containing cells, nucleic acid encoding therapeutic peptides, and the like, into interior body cavities, especially into the vasculature and the interior or exterior of the heart to induce or curtail angiogenesis.
In particular , there is a need in the art for a sterile closed system aspiration/injection unit for bedside use that can be used to aspirate bone marrow fluids, treat the fluids in a sterile environment, an reinject the treated bone marrow aspirate into a subject in need of bone marrow treatment. The present invention satisfies these needs and provides additional advantages.
The present invention solves many of the problems in the art by providing methods for introducing one or more precisely controlled therapeutic volumes of an angiogenesis promoting therapeutic fluid into a tissue surface in a subject in need thereof. The invention methods utilize a liquid injection system featuring a sterile container assembly that delivers repeated precisely controlled volumes of a liquid therefrom in a sterile condition.
In one embodiment, the invention methods for introducing an angiogenesis promoting fluid into a tissue surface comprise obtaining a sterile container assembly that comprises in liquid-tight arrangement:
a liquid-tight housing with an opening of reduced size relative to the housing; wherein the interior of the housing is maintained in a sterile condition and has a maximum internal volume in the range of about 3 ml to about 70 ml with a self-sealing puncturable sterile barrier covering the opening for receiving a hollow needle cannula; a pressure actuator in liquid-tight connection with the interior of the housing, wherein the pressure actuator repeatedly exerts a positive pressure on the therapeutic liquid contained in the interior of the housing so as to repeatedly expel a precisely controlled volume of the therapeutic liquid therefrom via the opening without septic contamination of the liquid and without uncontrolled loss of liquid therefrom; and a hollow needle in liquid communication with the interior of the housing. The invention method further comprises inserting the hollow needle into the tissue surface of the subject; and injecting a plurality of precisely controlled volumes of the therapeutic fluid contained in the sterile housing into a tissue surface of the subject via the hollow needle by actuating the pressure actuator to repeatedly exert the positive pressure on the therapeutic liquid in the sterile housing. By this method, the precisely controlled volume of the therapeutic angiogenesis-promoting fluid is repeatedly injected into the tissue surface of the subject in a substantially sterile condition.
In another embodiment, the present invention provides method for introducing one or more precisely controlled therapeutic volumes of an angiogenesis promoting therapeutic fluid in a sterile condition into a tissue surface in a subject in need thereof. The invention methods comprise a) obtaining a sterile liquid injection system comprising in co-axial arrangement: i) a hollow needle; ii) an invention sterile container; and (iii) a pressure actuator operationally coupled to the plunger handle of the sterile container; wherein the pressure actuator exerts a positive pressure on liquid in the sterile chamber so as to expel liquids therefrom in a controlled volume by distal movement of the container plunger one or more precisely controlled longitudinal distances; and wherein the method further comprises injecting a plurality of precisely controlled volumes of the therapeutic fluid contained in the sterile housing into a tissue surface of the subject via the hollow needle by actuating the pressure actuator to repeatedly exert the positive pressure on the therapeutic liquid in the sterile housing, whereby the precisely controlled volume of the therapeutic angiogenesis-promoting fluid is repeatedly injected into the tissue surface of the subject in a substantially sterile condition.
In another embodiment, the invention provides methods for processing bone marrow aspirate in a sterile condition by aspirating bone marrow liquid into a sterile container as described above via a hollow aspiration needle in fluid communication with the interior of the sterile container; and activating the pressure actuator so as to create sufficient partial vacuum within the interior of the housing to aspirate the bone marrow fluid into the sterile housing of the sterile container.